What quality is the MP3?
High-quality variable bitrate (roughly 190 kbps average) - transparent for speech and most music.
Is there a watermark or audio tag?
No. The MP3 is exactly the clip's audio, nothing added.
What if my video has no audio?
The conversion will fail with an error, since there is nothing to extract.
What are the limits?
Clips up to 60 seconds and files up to 100 MB. MP4, MOV and WebM are accepted.